Varicella zoster Virus IgG Antibody Levels in HIV Infected Patients Managed at Ryan White Clinics in Three South Carolina Counties

BACKGROUND: Infections due to Varicella-zoster virus (VZV) are common in HIV infected patients (HIVP), yet antibody levels to VZV are not routinely measured. To better understand host-VZV dynamics in HIVP plus assess the clinical utility of a commercial assay, IgG levels were measured and correlated with CD4 count, viral load (VL), history (HX) of Herpes zoster (HZ) and demographics. METHODS: Specimens were processed using a semi-quantitative assay. Results reported as an index: <135 consistent with “absence of immunity,” 135–165 “equivocal”, and >165 reflected “immunity.” Cut-off point reported as >4000. Statistical computations were performed in the R computing package (R Core Team 2017). Proportions compared using the exact chi-squared test. Highly skewed variables compared using the Mann–Whitney–Wilcoxon test, and censored variables compared via a generalization of MWW (log-rank). RESULTS: During 22 months, 426 HIVP enrolled, 284 (66%) males and 142 females; mean age was 44 and 51, respectively. Mean IgG index for all HIVP = 1,886, males = 1,971, females = 1,720 (P = 0.06). However, difference in median IgG was significant (1,730 vs. 1,477; P < 0.0001). Hx of HZ was elicited in 113 (27%), no gender difference (27% vs. 25%, P = 0.55). Frequency of IgG > 4,000 was not significant. HIVP subdivided into 3 age groups for further comparisons. Age≤ = 30: 79 HIVP, 87% of which were males, only 9 (11%) had Hx of HZ, lowest mean IgG = 1,686 and least HIV control. VL< 50 c/mL in 44%. Age 31 to 59: 274 HIVP with mean age of 47, mean IgG = 1,908, and 72% with VL < 50. A Hx of HZ in 86 (31%). Age ≥ 60: 73 HIVP with mean age of 65, mean IgG = 2006. Eighteen had Hx of HZ. Compared with second group, oldest group had better HIV control with VL < 50 in 79% (P = 0.039) yet mean IgG was similar (P = 0.33). Through a logistic regression analysis, the probability of HZ steadily increased as a function of age until about 55. IgG indexes >4,000 were also noted in 58 asymptomatic HIVP. CONCLUSION: Intermittent, asymptomatic VZV reactivation occurs in HIVP regardless of prior HZ. IgG < 135 predicted negative Hx of HZ. Pre-existing IgG may not protect against VZV reactivation. DISCLOSURES: All authors: No reported disclosures.